The invention relates to a stone catching basket instrument and to a method of producing such a multiwire basket instrument.
Stone catching basket instruments of this type are used for medical purposes for catching and removing stones or other concretions from human or animal tissue canals. In the present context, the term “wire basket” means that several wire sections are arranged around a longitudinal axis of a thus formed wire basket unit at a distance from one another extending essentially axially in the circumferential direction. In a basket-forming condition, they extend from a forward end area of the wire basket unit, while forming the wire basket, first expanding radially toward the outside and then again narrowing again radially toward the inside. The wire sections consist of a sufficiently elastic, not necessarily metallic material, frequently superelastic metal alloys being used.
Typically, the wire sections, when used as a wire basket, are held in a rearward end area by a receiving sleeve into which they can be pulled while the wire basket shrinks radially. In the pulled-out basket-forming condition, a stone or the like can move into the widened wire basket through the spaces between the wire sections, after which, by the pulling of the wire sections into the receiving sleeve, the wire basket is drawn together and the stone can be retained for the removal.
Medical stone catching basket instruments of this type are used in various designs, for example, for endoscopes. In the case of these applications, a forward end of the wire basket which is as short as possible is frequently desirable. In constructions, as disclosed, for example, in U.S. Pat. No. 6,013,086, the forward wire section ends or forward end bows of wire loops are held in a cylindrical end sleeve which therefore remains disposed in front of the actual wire basket area. In contrast, so-called tipless wire basket units have been suggested. Thus, International Published Patent Application WO 98/36694 A1 describes wire basket units where the basket-forming wire bows on the forward wire basket end, while forming narrower loops, are mutually linked loosely and thereby in an articulated manner. In German Patent Document DE 101 17 836 C1, it is suggested that the wire sections at the forward end be held in an articulated manner on a fixing body which may be designed such that, in the basket-forming condition, a virtually tipless forward end of the wire basket unit is obtained.
In the applicant's German Published Patent Application DE 10-2004-055375 A1, which is a later publication, a multiwire basket unit and a method of producing the same are described, which are based on a tubular piece from which the multiwire basket unit is formed in one piece, for the purpose of which the tubular jacket is subdivided into the wire sections by several axial slots spaced in the circumferential direction. The axial slots end while leaving a wire linkage area at a distance in front of a tube front end, and the wire sections are subsequently bent at the wire linkage area into a predefinable functional state. The content of this earlier patent application is thereby fully included here by reference in order to avoid unnecessary repetitions of text.
In the following, reference is made to this earlier patent application in an abbreviated manner as the “older application.”
A stone catching basket instrument of the initially mentioned type is disclosed in International Published Patent Application WO 2004/064597. In the case of this stone catching basket instrument, the wire linkage area is constructed as a centric predetermined breaking point area from which the individual wire sections originate. In this predetermined breaking point area, at least one of the wire sections is weakened or tapered in its thickness or width toward the center, are weakening perforations are provided.
In U.S. Published Patent Application US 2003/0187495 A1, a filtering instrument for endovascular medical applications is disclosed, in which a filter bag is held in a spread-open manner by a filter frame, which is formed by mutually connected wire sections as a cohesive wire complex. In this case, the wire complex is cut in one piece from an essentially plane raw material in a shape, where the wire sections extend essentially radially and are mutually cohesive at their radially interior end area by way of a wire linkage area designed in the shape of a rosette, the wire sections being bent with their free radially exterior ends by approximately 90° in a proximal direction and being guided together. In the distal direction, the filter bag adjoins the wire linkage area of the wire complex. Optionally, the wire complex can also be used as the filter without the filter bag.
U.S. Pat. No. 5,647,870 discloses a wire-basket-type electrode carrier structure for medical catheter applications, which is formed of several wire sections as a cohesive wire complex. In this case, the wire complex is cut in one piece from an essentially plane raw material in a shape in which the wire sections extend essentially radially and are mutually cohesive at their radially interior end area by way of a disk-shaped wire linkage area provided with a central opening. The free radial exterior ends of the wire sections are bent by approximately 90° in a proximal direction and are guided together, at least one of the wire sections consisting of a flexible metallic or plastic material carrying an electrode element.
The invention is based on the technical problem of providing a stone catching basket instrument of the initially mentioned type, which can be implemented at comparatively low expenditures, and a pertaining production method.
The multiwire basket unit of the stone catching basket instrument according to the invention can be formed of a cohesive wire complex, in which the wire sections are connected with one another and which is cut in one piece from an essentially plane raw material, the cut-out wire complex being bent into a wire basket unit. The cut-out wire complex contains essentially radially extending wire sections which are mutually cohesive at a radially interior end while forming a rosette-shaped wire linkage area. For forming the wire basket, the radial wire sections, for example, by means of their radial exterior ends, can be bent out of the cutting plane by approximately 90° and can be guided together. The wire linkage area forms the other axial end of the wire basket unit situated opposite the guided-together wire section ends, specifically the forward wire basket end which is distal when in use. Different designs are conceivable for the rosette-shaped wire basket linkage area, which designs, in turn, determine the shape of the corresponding axial wire basket end area.
The invention thereby permits the production of the multiwire basket unit from a plane raw material, such as a metal sheet or foil material. As required, the wire complex can be designed such that, in the case of a corresponding bending out of the plane, for example, a virtually tipless wire basket is obtained, which is used as a catching basket. The rosette shape of the wire linkage area, which particularly may also be a multiple rosette shape, is particularly advantageous in order to achieve a tipless wire basket end of a high stability and strength and/or permit a secure radial folding-together and re-unfolding of the wire basket, for example, by a pulling or pushing into a receiving sleeve and a pulling out again from a receiving sleeve.
While, during the cutting-out of the wire complex with the cohesive wire sections from a tubular piece, as provided in the older application, attention must possibly be paid to the fact that the cutting operation, for example, by means of a laser beam, does not continue on the respectively opposite tubular jacket side, the cutting of the wire complex out of an essentially plane raw material generally is clearly simpler. Specific characteristics, which may occur as a result of the tubular curvature when cutting the wire complex out of a tubular piece, do not exist from the start when, according to the invention, essentially plane sheet material is used as the raw material. Generally, the use of essentially plane raw material permits a very precise and advantageous guiding and shaping of the cuts during the cutting operation, for example, by means of a cutting laser. Furthermore, plane sheet material is generally more cost effective than tubular material.
In an advantageous embodiment of the invention, the raw material and thus the multiwire basket unit consists of a superelastic material. As a rule, such materials also have a shape memory. The latter can be utilized for selecting the functional state of the wire sections mutually connected in the wire complex as the dimensionally stable state, so that the wire sections will automatically assume their functional state when they are not prevented therefrom by external forces, for example, by the introduction into a receiving sleeve or are changed into a different state.
As a further development of the invention, the cutting-out of the wire complex may take, for example, by laser cutting or water jet cutting.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.